EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Numerator:
Net income	$ 13,023	$ 37,350
Denominator:
Weighted average basic shares (in shares)	38,874	31,426
Dilutive potential common shares (in shares)	410	834
Weighted average fully diluted shares (in shares)	39,284	32,260
Earnings per share:
Basic (in dollars per share)	$ 0.34	$ 1.19
Diluted (in dollars per share)	$ 0.33	$ 1.16
Outstanding common stock equivalents having no dilutive effect (in shares)	39	88